It is ironic that in a world where childhood malnutrition plagues many developing countries, childhood obesity has become one of the leading health scourges in advanced economies. The World Bank estimates that over a third of all children in Indonesia, for example, suffer from stunted growth, confronting them with the risk of lifetime effects on fitness and cognitive development. Yet the plight of malnourished children in the developing world does not make obesity in the advanced countries any less of a problem.
Indeed, though perhaps not on a par with global warming and looming water shortages, obesity - and especially childhood obesity - nonetheless is on the short list of major public-health challenges facing advanced countries in the 21st century, and it is rapidly affecting many emerging-market economies as well. Yet solving it poses much more difficult challenges than the kind of successful public-health interventions of the last century, including near-universal vaccination, fluoridation of drinking water and motor-vehicle safety rules.
The question is whether it is realistic to hope for success unless the government resorts to far more blunt instruments than it currently seems prepared to wield. Given the huge impact of obesity on healthcare costs, life expectancy and quality of life, it is a topic that merits urgent attention.
The United States leads the world in obesity and is at the cutting edge of the debate. Almost everyone agrees that the first line of defence ought to be better consumer education. First Lady Michelle Obama's "Let's Move" educational campaign aspires to eliminate childhood obesity in a generation, though its impact so far remains unclear. Other efforts include appeals by celebrities like the chef Jamie Oliver and attempts to use peer-based learning, such as the Sesame Street-inspired platform Kickin' Nutrition (full disclosure: the creator is my wife).
Yet although education is essential to fight obesity, it is far from clear whether it will be enough in a food environment dominated by large corporations with deep pockets and every incentive to cultivate excessive consumption. Commercial television programmes aimed at children are replete with advertising for processed food of dubious value to human health. And for every celebrity who donates time to fighting obesity, there are a dozen who accept large payments to hawk products, such as ultra-sugary drinks, that are arguably the tobacco of our generation. It is hard for non-profits to compete with the production values embodied in Beyonce's Pepsi commercial or Taylor Swift's Diet Coke commercial.
The causes of obesity are complex, and the science of understanding human behaviour is embryonic; but it is not hyperbole to call the problem an epidemic. According to the Centers for Disease Control and Prevention, roughly 18 per cent of children aged six to 11 in the United States are not just overweight but obese.
The risks posed by this epidemic are manifold, but the main one is that childhood obesity begets adult obesity, with significantly increased risks of diabetes and heart disease. Indeed experts estimate that more than 18 per cent of all adults in the advanced economies are obese. Even more stunning are estimates that roughly nine per cent of all Americans - and a similar percentage of adults worldwide - have diabetes.
Yet politicians push back on Big Food at their peril. When the popular former mayor of New York City, Michael Bloomberg, attempted to ban large sugary drinks, public opinion - not to mention the New York State Court of Appeals - rejected the effort, despite support from medical experts. Many commentators, even those sympathetic to Mr Bloomberg's goal, argued that it was wrong to try to legislate consumer behaviour so bluntly. Yet when one considers other successful efforts to improve public health over the last five decades - for example, smoking bans, seat-belt laws and speed limits - one finds that legislation typically supplemented education.
A less intrusive approach to influencing food choices might be to institute a retail tax on all processed foods - not just sugary drinks - and an offsetting subsidy on non-processed foods. In the long run, low-income families (which suffer the most from obesity) would be the greatest beneficiaries. And in the short term, any income effects could be offset by increased transfers. Together with the medical researchers David Ludwig and Dariush Mozaffarian, I have proposed an outline of such an approach.
Obviously, some processed food are far worse than others. A more complex breakdown is possible, and other ideas should, of course, be vetted and discussed. But our approach has the important practical advantage of simplicity. What must be understood, above all, is that US consumer culture is dominated by a food industry that exploits people's natural joy in eating and transforms it (in many cases) into something that is addictive and destructive. Any visitor to the United States can readily see the pervasiveness of the problem.
The right place to start to address it is by creating a better balance between education and commercial disinformation. But food is so addictive, and the environment so skewed toward unhealthy outcomes, that it is time to think about broader government intervention. That should certainly include vastly enhanced expenditures on public education; but I suspect that a long-term solution will have to involve more direct regulation, and it is not too soon to start discussing the modalities.
The writer, a former chief economist of the International Monetary Fund, is professor of economics and public policy at Harvard University
Copyright: Project Syndicate, 2015